Studies will be carried out to determine if the defects in the excitation-contraction properties of the cardiovascular muscles are related to the cyclic AMP-dependent biochemical processes. The cyclic AMP-dependent protein kinases from the cytosol and the microsomal fractions will be obtained and the distribution of their isoenzymes will be determined by subjecting these fractions to DEAE-cellulose columns. Comparison of the distribution of the isoenzymes between the WKY and the SHR will enable us to determine if there is any alteration in one or both isoenzymes in the hypertensive animals. The number and the extent of phosphorylation of the phosphate acceptor protein will be examined by a combination of gel electrophoresis and gel filtration techniques. Further studies will involve chemical and physical characterization of the partially purified subunits (regulatory and catalytic subunits) of the corresponding isoenzymes to examine the specific nature of alteration at the subunit level. The information obtained from this work will be utilized the elucidate the mechanism of the protein kinase action in the normal cardiovascular tissue and its involvement (if any) in causation of hypertension.